Polishing apparatus



Aug. 4, 1959 v E. BUHR L 2,897,633

POLISHING APPARATUS Filed Jan. 30, 1957 IN VEN TORS agT.

ignited S ate Pat 2,897,633 POLISHING APPARATUS Erich Biihr,Stuttgart-Feuerbach, and Paul Wellner, Geislingen (Steige), GermanyApplication January '30, 1957, Serial No. 637,202

Claims priority, application Germany February '11, 1956 11 Claims. c1.51-7 The present invention relates to a polishing apparatus.

pressed against the inner surface of the rotating polishing mass.

In apparatuses of this type the drum is normally open "at the top, and asuitable stationary cover is provided for covering the same, such coverbeing formed with one or more openings therethrough through which thework pieces may be dipped into the interior of the drum. Usually, theupstanding side wall of the drum is formed with an inwardly extendingflange, and the cover has an outer rim which is but slightly smaller indiameter than the outer rim of the flange so that a relatively narrowgap is formed between the rotating flange and the stationary cover.Inasmuch as contact between the work pieces and the rotating polishingmass will inevitably force a number of individual granular particles outof the polishing mass, some of these particles will tend to escape fromthe interior of the drum by way of this gap. It has therefore been foundnecessary in some way to prevent the egress "of granular material.

It has been sought to accomplish this result by maintaining the gapextremely small. However, this solution has not proved satisfactoryinasmuch as in order to maintainthe gap very small while at the sametime affording suflicient clearance between the inner rim of the flangeand the stationary cover to permit free rotation of the drum, the lattermust be mounted in such a manner as to be capable of rotating withoutundergoing any perceptible wobbling. Such mounting arrangements arerather expensive and complicated, particularly when a drum is involvedthe diameter of which is of the order of 3 meters.

Alternatively, it has been suggested to provide sealing means, such as alabyrinth seal, for preventing the loss of granular particles. However,such seals have not been 'found to be particularly effective, especiallysince even with such seals the mounting of the drum must be such asto'permit substantially wobble-free rotation.

. It is therefore an object of the present invention to proportion.

a rotatable substantially cup-shaped drum having a bottom portion and.an annular upstanding wall-portion, covering means arranged near theupper rim of the wall portion but spaced therefrom so that an annulargap'is formed between the rim and the covering means, and means formoving air through the gap from the exterior of the drum to the interiorthereof during rotation of the drum. As a result, a mass of granularmaterial in the drum will, during rotation thereof, be centrifugedagainst the upstanding wall while individual granular particles will beprevented [from leaving the interior of the drum through the gap by theair moving therethroug'h in the opposite direction.

The novel features which are considered as characteristic for theinvention are set forth in particular in the appended claims. Theinvention itself, however, both as to its construction and its method ofoperation, together with additional objects and advantages thereof, willbe best understood from the following description of specificembodiments when read in connection with the accompanying drawings, inwhich: I

Fig. 1 is an elevational view, partly in section, of one embodiment ofthe present invention;

Fig. 2 is a sectional view on a larger scale of a detail of the presentinvention;

Fig. 3 is a fragmentary sectional view taken substantially along line3-3 of Fig. 2; and

Fig. 4 is a sectional view on an enlarged scale of a differentembodiment of the detail illustrated in Fig. 2. Referring now to'thedrawing, and to Figs. 1-3 thereof in particular, there is shown ahousing or support '1 in which a substantially cup-shaped drum 3 isarranged. The drum 3 has a bottom portion 4 carrying a stud 5 which isrotatably received by a bearing 6 so that the drum is rotatably mountedonthe support 1. The drum also has an upstanding annular wall portion 7the height of which is relatively small in comparison to diameter of thedrum. The wall portion 7 is formed with an inwardly extending annularflange portion 8 which carries an annular element 9 constituting theinner rim of the flange The drum 3 carries a friction ring 10 which ismounted on the outer surface of the wall portion 7 so that the drum maybe. rotated by a rotatably mountedfriction roller 11, the latter beingdriven in any suitable manner (not shown).

The support 1 also carries a stationary cover 2 which is formed with adownwardly depending annularwall portion 2a which carries anotherannular element 13. The arrangement and construction of the parts issuch that elements 9 and 13 are substantially concentric and formbetween themselves a relatively large and preferably downwardly taperinggap 14.

The drum contains a mass of granular material the quantity being soselected that when the drum is rotated, substantially all of thegranular particles are centrifuged against the upstanding wall portion 7and into the space beneath the flange portion 8 so as to form an annularpolishing mass 12.

The support 1 also supports one or more work piece carriers 15 which arepreferably displacedequal angular distances from each other. Eachcarrier 15 extends over the cover 2 and includes a swingably mounted arm15 to the free end of which one or more chucks 17 are atthe provision ofa polishing apparatus of the above type in mainly resides in a polishingapparatus which includes.

tached, the chucks extending in a direction transverse to the arm 16.Each chuck, only oneof which is shown in Fig. 1, is adapted to grasp awork piece 18, the construction of the chuck preferably being such as topermit rotation or oscillation of each work piece about its own axis sothat the'entire surface of the work piece which is'to be polished may beexposed to the action of the polishing mass 12. As may readily be seenfrom the drawingeach arm is swingable to and from an operative positionwherein the work piece 18 is engaged by the polishing mass 12constituted by the centrifuged particles of the granular material.Theposition of the arm 16 in which the workpiece out of the drum isshown in dotted lines. -'In order to permit the arms 16 to be moved intoand, out of the drum, the cover 2 is formed with one or more openings19, depending upon the number of work piece carriers 15, each openingbeing in angular registration with its respective carrier so that thecorrespond ing area 16 may pass through the opening.

As the polishing operation proceeds, individual granular particles willbe deflected from their normally circular paths. Most of these particleswill fall to the bottom of the drum, where they will again be subjectedto the rotation of the drum and be centrifuged back into the annularpolishing mass 12. This eflect may be enhanced by providing adome-shaped insert 20, or by imparting suchv a shape to the bottomportion 4 itself. However, a considerable number of particles will tendto move upwardly and tend to escape from the interior of the drum 3' byway of the gap 14. According to the present invention this is preventedby providing means for moving air through the gap from the exterior ofthe drum to the interior thereof during rotation of the drum. In thisway, the egress of individual granular particles through the gap 14 willbe prevented by air flowing therethrough in the opposite direction.Also, the air thus blown into the drum serves to cool the polishing mass12.

' The means for moving air through the gap 14 may be in the form of ablower arrangement which incorporates an annular nozzle 21 which isarranged below that portion of the cover 2 which is exterior of thedepending clockwise rotation of the drum 3 as seen from above in Fig. 1,cause air to flow downwardly through the gap 14.

While the arrangement shown in Fig. 4 may be used in conjunction withthe above-described blower means, it has been found that if the drum isrotated sufiiciently rapidly, the blades 30a alone can be relied upon toact as the means for moving air through the gap 14. Consequently, apolishing apparatus incorporating the structure shown in Fig. 4 may beconstructed without the above-described blower means.

A rake 32 having prongs 33 may be mounted on the cover 2 in such amanner that the prongs extends-into the granular material forming theannular polishing mass 12, thereby continuously raking the latter duringrotation of the drum. While this has the desirable result ofcontinuously bringing fresh particles into contact with the work piecesbeing polished, the turbulence of the air in the drum isincreased,thereby causing a larger number of granular. particles to seekegress'through the gap 14.

This, in turn, increases the need for efliciently preventing the flow ofparticles through the gap, and this is accomplished by the presentinvention.

It will be understood that each of the elements described above, or twoor more together, may also find a useful application in other types ofpolishing apparatuses diifering from the types described above. 7

While the invention has been illustrated and described embodied apolishing apparatus in which the drum is formed with an upper inwardlyextending flange, it is not intended to be limited to the details shown,since various modifications and structural changes may be made withoutdeparting in any way from the spirit of the present invention.

duit 25 by means of one or more radial conduits 24 ing 19 formed in thecover 2. The hoods are placed in communication with a central conduit28, which prefer ably encompasses and is concentric with the centralconduit. 25, by means of branch conduits 29. The conduit 28 isconnectedto a suction device (not shown) by means of another conduit 27 so thatany particles seeking to leave the interior of the drum '3 by way of theopenings 19 will be sucked in and may in this way be salvaged. In orderto accomplish this, the suction device is so adjusted that'it will suckin slightly more air than is blown into the drum 3 through the gap 14 soas to prevent air and consequently granular particles from flowing outof the hoods into the surrounding atmosphere.

It has been found expedient to place a cyclone separator orthe like incommunication with the suction means for extracting therefrom granularparticles of at least apredetermined mass, so that relatively largeparticles may be separated from the air suckedin by the suckingdeviceand later be returned to the drum.

If desired, baflle means may be arranged in the gap for additionallyimpeding the egress of granular particles overlap each at least one nextadjacent bafile'element, as may be seen in Fig. 3. Theembodiment showninFig. 4 diifers from the above- ;described one in that baflle elements30a are carried by thelrotating annular element 9.rather than thestationary element 13.. .The bathe elements act therefore not "iOIfiYQS'deflECtOIS; but also as fan blades which, during Without furtheranalysis, the foregoing will so fully reveal the gist of the presentinvention that others can by applying current knowledge readily adapt itfor various applications without omitting features that, from thestandpoint of prior art, fairly constitute essential characteristics ofthe generic or specific aspects of this invention and, therefore, suchadaptations should and are intended to be comprehended within themeaning and range of equivalence of the following claims. I

What is claimed as new and desired to be secured by Letters Patent is: v

1. In a polishing apparatus, in combination, support means; asubstantially cup-shaped drum mounted on said support means for rotationrelative thereto, said drum having a bottom portioman upstanding annularwall portion, and an inwardly directed annular flange portion;stationary covering means on said support means and arranged near theinner rim of said flange portion-but spaced therefrom so that said drummay rotate freely relative to said covering means and so that an annulargap is formed between said flange portion and said covering means; andblower means including nozzle means arranged above said gap for movingair through said gap from the exterior of said drum to the interiorthereof during rotation of said drum, whereby a mass of granularmaterial in said drum will during rotation thereof be centrifugedagainst said upstanding wall portion thereof into the space beneath saidflange portion while individual granular particles will be preventedfrom leaving said space through said gap by the air moving therethroughin the opposite direction.

2. In a polishing apparatus, in combination, support means; asubstantially cup-shaped drum mounted on said support means for rotationrelative thereto, said drum having a bottom portion, an upstandingannular wall portion, and an inwardly directed annular flange portion;stationary covering means on said support means and arranged near theinner rim of said flange portion but 'spaced therefrom so that said drummay rotate freely arranged above said gap and being in registrationtherewith for moving air through said gap from the exterior of said drumto the interior thereof during rotation of said drum, whereby a mass ofgranular material in said drum will during rotation thereof becentrifuged against said upstanding wall portion thereof into the spacebeneath said flange portion while individual granular particles will beprevented from leaving said space through said gap by the air movingtherethrough in the opposite direction.

3. The combination defined in claim 2, and deflector means arranged insaid gap for additionally impeding the egress of granular particlesthrough said gap.

4. The combination defined in claim 3 wherein said deflector meansinclude a plurality of bafiie elements on said covering means andextending across said gap, said baflle elements being inclined to aplane normal to the axis of said drum, each bafile element being soarranged as to overlap at least one of its next adjacent bafiieelements.

5. In a polishing apparatus, in combination, support means; asubstantially cup-shaped drum mounted on said support means for rotationrelative thereto, said drum having a bottom portion, an upstandingannular wall portion, and an inwardly directed annular flange portion;stationary covering means on said support means and arranged near theinner rim of said flange portion but spaced therefrom so that said drummay rotate freely relative to said covering means and so that an annulargap is formed between said flange portion and said covering means; andmeans for moving air through said gap from the exterior of said drum tothe interior thereof during rotation of said drum, said moving meansincluding nozzle means arranged above said gap and blower means forblowing air therethrough, said moving means further including aplurality of blades in said gap and connected to said drum for rotationtherewith, said blades being so constructed and arranged as to cause theflow of air into said drum through said gap during rotation of saiddrum, whereby a mass of granular material in said drum will duringrotation thereof be centrifuged against said upstanding wall portionthereof into the space beneath said flange portion while individualgranular particles will be prevented from leaving said space throughsaid gap by the air moving therethrough in the opposite direction.

6. In a polishing apparatus, in combination, support means; asubstantially cup-shaped drum mounted on said support means for rotationrelative thereto, said drum having a bottom portion, an upstandingannular wall portion, and an inwardly directed annular flange portion;stationary covering means on said support means and arranged near theinner rim of said flange portion but spaced therefrom so that said drummay rotate freely relative to said 'overing means and so that an annulargap is formed between said flange portion and said covering means; andmeans for moving air through said gap from the exterior of said drum tothe interior thereof during rotation of said drum, said moving meanscomprising a plurality of blades in said gap and connected to said drumfor rotation therewith, said blades being so constructed and arranged asto cause the flow of air into said drum through said gap during rotationof said drum, whereby a mass of granular material in said drum willduring rotation thereof be centrifuged against said upstanding wallportion thereof into the space beneath said flange portion whileindividual granular particles will be prevented from leaving said spacethrough said gap by the air moving therethrough in the oppositedirection.

7. In a polishing apparatus, in combination, supportmeans; asubstantially cup-shaped drum mounted on said support means for rotationrelative thereto, said drum having a bottom portion, an upstandingannulan wall portion, and an inwardly directed annular flange portion;stationary covering means on said support means and arranged near theinner rim of said flange portion but spaced therefrom so that said drummay rotate freely relative to said covering means and so that an annulargap is formed between said flange portion and said covering means; meansfor moving air through said gap from the exterior of said drum to theinterior thereof during rotation of said drum, whereby a mass ofgranular material in said drum will during rotation thereof becentrifuged against said upstanding wall portion thereof into the spacebeneath said flange portion while individual granular particles will beprevented from leaving said space through said gap by the air movingtherethrough in the opposite direction; and at least one work piececarrier capable of carrying a work piece to be polished, said carrierbeing mounted on said support for swinging movement relative theretointo and out of an operative position wherein a work piece carried bysaid carrier is located in said space so as to be contacted and polishedby a mass of gnanular material centrifuged against said upstanding wallportion of said drum during rotation thereof.

8. The combination defined in claim 7 wherein said covering means isformed with :at least one opening therethrough through which saidcarrier extends when the same is in its operative position.

9. The combination defined in claim 8 wherein said carrier is soarranged that when it occupies its operative position, it extends oversaid annular gap.

10. The combination defined in claim 8, and suction means arrangedexteriorly of said drum and being in communication with said openingthrough said covering means, whereby granular particles escaping fromsaid drum through said opening may be collected and salvaged.

11. The combination defined in claim 10, wherein said moving meansinclude a nozzle arranged [above said gap and blower means for blowingair therethrough, and wherein said blower means and said suction meanseach include a conduit, said conduits being arranged coaxially with eachother throughout at least a portion of their lengths.

References Cited in the file of this patent UNITED STATES PATENTS2,238,743 Lykken Apr. 15, 1941 2,664,676 Cuppers Jan. 5, 1954 2,699,293Svendsen Jan. 11, 1955 2,734,317 Bond Feb. 14, 1956

